Experience in teaching doesn't tend to sharpen my abilities; rather it dulls them. It is evaluated experience that improves my skills.
—Howard Hendricks

Most people think experience is the name of the game, that the longer a person teaches, the better he or she gets. Nonsense. Just as ripping through wood dulls the teeth of a carpenter's saw, so experience tends to wear away my edge. I have found only evaluated experience sharpens my skills. Evaluation hones the edge.

Teaching without evaluation can erode my effectiveness in many ways. Poor methods become ingrained habits. I can assume I'm doing better than I really am and become complacent. I can conclude something works when it actually doesn't. I can lose touch with my audience, teaching in a vacuum. Also, time exaggerates my idiosyncrasies rather than lessening them. And without anything to keep me on my toes, I can get sloppy.

That's why, like the carpenter who painstakingly files each tooth on his crosscut saw, I evaluate every session ...